1. Field of the Invention
This invention relates to a motor operated camera arranged to have various operations thereof performed by the outputs of motors.
2. Description of the Prior Art
Electric motor operated cameras of the kind having a plurality of parts individually driven by switching one transmission system over to another for transmitting the driving force of a motor have been proposed during recent years. Heretofore, the motor operated camera of this kind has been arranged to drive a plurality of parts one after another by mechanically detecting a load and by switching a clutch accordingly. However, the motor is allowed to rotate only in one direction. Energy is wasted for switching the clutch. Further, the mechanical arrangement is complex and produces a disagreeable sound in switching the clutch.
In another prior art device, a transmission system is arranged to be switched by means of a planet gear. It has solved the problem of the disagreeable sound as the transmission system is readily switchable by changing the rotating direction of the motor without making noises. However, since the switching or change-over is effected by a revolving force, the parts to be driven by transmission is rotatable only in one direction and is incapable of being driven for reverse rotation. Therefore, in cases where the parts to be driven must be driven to rotate back and forth, as in the cases of automatic focusing and power zooming devices, these parts are respectively provided with motors for forward and backward rotations separately from each other. However, such arrangement has necessitated the use of a greater number of parts and thus resulted in an increased cost and a larger size of the camera.
To solve these problems, there has been proposed a device which is not only capable of permitting driving operations on a plurality of parts with a single motor by shifting a gear interlocking system by means of an external operation parts but also capable of driving them back and forth. However, this device necessitates an operation from outside as required. Besides, the arrangement has given a disagreeable feeling when operated from outside. There has been proposed another device which permits an automatic operation with electromagnetic clutches arranged on both output shafts of a motor. That device, however, necessitates use of two electromagnetic clutches which are expensive in addition to the motor and thus has caused an increase in cost. Besides, during operation, electric currents must flow also to the electromagnetic clutches to lower efficiency in terms of energy consumption. It has been a further disadvantage of that device that the great moment of inertia of the electromagnetic clutch degrades the controllability of them in bringing them to a stop at predetermined positions.
In addition to these prior art devices, there has been proposed a driving force transmission device wherein a driving gear is arranged to be movable in a thrust direction to change over the engagement of the driving gear from one follower gear to another, so that forward and backward driving operations can be performed in two channels. However, the driving gear is moved generally by means of a plunger or the like, for example, with an electromagnet. Therefore, the arrangement necessitates use of additional driving force generating means for generating a driving force required for the above-stated change-over of engagement. Further, at the time of the change-over movement in the thrust direction, the teeth of the driving gear might collide with those of the follower gear to cause some damage. Besides, this possibility necessitates some suitable impact absorbing arrangement.